Refractory masonry wall bounding a space which receives hot gas

ABSTRACT

The invention relates to a refractory masonry wall bounding a space which receives hot gas, and being pierced by a gas duct connection, into the space, e.g., a hot blast stove for preheating air for a blast furnace, with a hot air outlet duct. According to the invention the wall has adjacent the space a layer of refractory masonry which includes a ring of bricks surrounding the gas duct at its entry into the space, there being a joint allowing relative slinding between the layer, including the ring of bricks, and outwardly adjacent refractory masonry of the wall. Thus vertical thermal expansions of the refractory lining of the vessel in the area of the duct connection are possible without damage, undue stresses and overheating of the outer steel jacket of the vessel.

United States Patent Weber Apr. 9, 1974 REFRACTORY MASONRY WALL 3,416,780 12/1968 Hanna 432/248 BOUNDING A SPACE WHICH RECEIVES 3,366,375 1/l968 Jones 432/252 HOT GAS 2,987,856 6/1961 Longenecker 432/252 2,850,89l 9/1958 Scheib 432/247 Inventor:

Assignee: Hoogovens Ijmuiden B.V., ljmuiden,

Netherlands Filed: Aug. 30, 1972 Appl. No.: 284,728

Foreign Application Priority Data Sept. 7, 1971 Netherlands 71 12336 U.S. c1.., 432/251, 432/252, 110/1 A, 432/248 1111. c1. F23b 1/00 Field of Search 432/247-252,

432/119, 214, 219; 266/43, 29, 30; llO/l A, l B, l R, 99 R; 52/415, 416, 484, 576, 597, 745, 749 DIG, 2

References Cited UNITED STATES PATENTS 9/1970 Hyde 432/252 Primary Eraminer.lohn J. Camby Assistant E.\'aminerHenry C. Yuen Attorney, Agent, or FirmHall & Houghton 5 7 ABSTRACT The invention relates to a refractory masonry wall bounding a space which receives hot gas, and being pierced by a gas duct connection, into the space, eg, a hot blast stove for preheating air for a blast furnace, with a hot air outlet duct. According to the invention the wall has adjacent the space a layer of refractory masonry which includes a ring of bricks surrounding the gas duct at-its entry into the space, there being a joint allowing relative slinding between the layer, including the ring of bricks, and outwardly adjacent refractory masonry of the wall. Thus vertical thermal expansions of the refractory lining of the vessel in the area of the duct connection are possible without damage, undue stresses and overheating of the outer steel jacket of the vessel.

9 Claims, 4 Drawing Figures This invention relates to a refractory masonry wall, for a space which receives hot gas, which is pierced by a gas duct and also to a structure including such a wall, e.g., a blast furnace stove, hot blast stove, or cowper stove of the regenerator type, which is used for preheating the air for a blast furnace.

Structures to which the invention are particularly applicable are those within which high temperatures prevail of an order of magnitude which require a refractory masonry structure for the inner wall of the structure. A particular example of such a structure is the above-mentioned hot blast stove, used for supplying pre-heated air at a temperature of 800 to 1,400 C to a blast furnace for iron ore reduction. Although the invention will for the most part in the following specification be described and explained in terms of such a hot blast stove, it is not restricted thereto. In such a hot blast stove the outlet duct for the hot air is connected to a cylindrical wall part of the stove.

In a hot blast stove, particularly if it is used for very high temperatures, difficulties often occur in the region of the outlet duct for the heated air. These difficulties are the result of damage or even collapse of the refractory lining or masonry structure in the region where the cylindrical wall part joins the outlet duct, which causes the temperature of the steel jacket surrounding the stove to become too high, so that this also threatens to collapse. It often happens that the behaviour of this region becomes a critical and crucial factor in the operation of the entire blast furnace plant and special emergency measures or even .a temporary interruption of the pig iron production may become necessary.

According to a usual method'of building the masonry structure of this region, the masonry structure of the outlet duct extends inwardly into the stove to the inner wall of the masonry structure of the cylindrical wall of the vessel. This makes the brick laying very simple and keeps to a minimum the number of refractory bricks of non-standard shapes.

The present invention is, however, based upon the realization that it is exactly this known manner of laying bricks which is in part responsible for the difficulties discussed above. Such difficulties particularly have their origin in the fact that the masonry structure of the outlet duct, whichas said extends inwardly into the stove can form an obstacle to movement of the masonry structure of the cylindrical wall part as a result of thermal expansion. The problem becomes greater the higher the position of the outlet duct in the vessel.

According to this invention there is provided a wall bounding a space which receives hot gas and being pierced by a gas duct connection into the space, the wall having adjacent the space a layer of refractory masonry which includes a ring of bricks surrounding the gas duct at its entry into the space, there being a joint allowing relative sliding between the layer, including the ring of bricks, and outwardly adjacent refractory masonry of the wall. In this construction, when the temperature within the vessel varies considerably, so that the inner layer of the masonry wall expands thermally and is displaced at the gas duct connection in a direction transverse to the axial direction of the gas duct, it is possible for the refractory bricks around the opening of the duct to the interior of the structure to move freely together with the remainder of the inner layer.

In some cases, particularly if the temperature gradient in the refractory wall is considerable, it will be preferable to have more than one sliding joint in the wall, so that two or more layers of the wall are free to slide relative to one another and to the outwardly adjacent masonry when the temperatures varies when heating up or cooling down.

Thus in a wall according to the invention preferably the said layer is the innermost of a plurality of refractory masonry layers, each including a ring of bricks surrounding the gas duct, there being a joint allowing relative sliding between the or each pair of adjacent said layers and between the outermost layer and outwardly adjacent refractory masonry of the wall. I

It is remarked that in a wall according to the invention the said sliding joint or joints extend right to the face of the masonry bounding the gas duct, so that it is possible that hot gases may penetrate into the refractory structure, which could be seen as a disadvantage. It has, however, appeared that it is adequate to fill up of the sliding joints with refractory substances such as ceramic wool or felt and the like in order to avoid the penetration of hot gases into the joints. Nevertheless sufficient freedom for sliding movements between the different layers is left. In this manner the parts of the masonry structure can move alongside one another without mutual disturbance, so that this structure can entirely remain intact. It has appeared that in this way the danger of the occurrence of hot zones in the outer wall of the vessel in the region of the connection outlet duct can entirely be avoided.

Since there may be several layers in the masonry structure of the vessel which are able to move with respect to each other during heating up, an originally (when cold) smooth inner surface of the masonry surrounding the gas connecting duct may have mutually displaced cylindrical rows of bricks after heating up. This could result in accelerated wear of the protruding edges thus generated by erosion, and moreover the resistance to flow within the gas connecting duct will be considerably increased by the protruding edges. This disadvantage can be avoided if the or each said ring of bricks in the cold condition of the wall is offset transversely with respect to the duct from the desired position in alignment with the duct by an amount such that, on heating to operating temperature, the expansion of the layer of which the ring is'a portion brings the ring into the desired aligned position. This amount may correspond to the free displacement of said ring or rings when the wall is heated to operating temperature which is the calculable free thermal expansion of the inner layers of the masonry structure along the sliding joints. In the case where the wall is the wall of a hot blast stove with a so-called ceramic burner being mounted within the wall in the lower end of the burner stack, the calculation will take into account the operating temperature to be expected in the several layers of the masonry structure, the expansion of these layers on heating to this temperature being calculated from the top face of the ceramic burner to the outlet for the heated air (hot blast). In general such a calculation will be possible for a particular case and will not cause difficulties to the expert.

It is important that the said ring or rings of refractory bricks have adequate stability in themselves and are anchored correctly in the surrounding masonry. This latter requirement is particularly of importance if, as a result of an expansion of the masonry structure surrounding the gas duct further from the connection of the duct into the hot gas space, the ring or rings would be stressed by a compressive force tending to push it or them into the space. It is preferred according to the in vention that the bricks in the or each said ring have interlocking projections and recesses in their mutually abutting surfaces. Preferably each adjacent pair of bricks has two pairs of interlocking projections and recesses, one pair extending longitudinally at an angle to the other pair. Thereby higher stability is obtained and a relative sliding of the bricks with respect to each other is not possible.

If the wall has, in the area of the duct connection, a curved inner surface, it is preferred that the bricks of the or each said ring have, opposite their faces which face into the gas duct, faces which are in planes substantially perpendicular to the said inner face. As a result of the curvature of the inner wall the ring of bricks is thereby as it were wedged and anchored in the surrounding masonry structure.

So that the ring or rings-of bricks may not be put under compression by the masonry structure surrounding the gas duct it is preferred that the gas duct, further from the hot gas space from the said ring or rings of bricks, is bounded by masonry which is joined to the adjacent said ring of bricks by a joint allowing-relative sliding and is provided with an expansion gap to allow expansion in the direction away from the hot gas space.

The shape of the said ring or rings of bricks may be of any suitable shape to correspond with the shape of the gas duct.

The invention also provides a structure, particularly a regenerator stove for preheating air for a blast furnace which has a wall according to the invention as described above.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings,.in which:

FIG. I shows part of the wall' of a hot blast stove for a blast furnace in horizontal section;

FIG. 2 shows part of the wall (when cold) of FIG; 1 vertical section along the line IIlI of FIG. 1; i j FIG. 3 is a part cross-section of through the middle of the bricks ll of the ring 6 looking in the direction of the arrow III of FIG. 2;

FIG. 4 is a sectional view through both rings 6, 7 of bricks showing their end faces lying in axial planes of the duct, looking in the direction of the arrow IV of FIG. 3.

The air preheater, cowper or hot blast stove which preheats the air to be fed a blast furnace has a hot air outlet connection which is shown in horizontal section in FIG. 1. The structure of the air preheater is in the main of a known and usual type, e.g., as shown in British Pat. Nos. 1,212,177 and 1,250,443 and U.S. Pat. Nos. 3,550,918 and 3,642,262, so that it need not be described in detail here.

The air preheater has an outer steel jacket 1 which is connected to an outer steel wall 2 of the hot air outlet duct 4. The wall 2 terminates outwardly in a flange 3. In the usual way there may be a slide valve for the heated air hot blast valve or an expansion joint connected to this flange. Within the steel wall 2 of the duct there is a masonry wall. A wall of refractorybricks I ing temperature, the steps 16, 17 disappear and the within the jacket 1 of the preheater has an inner surface 5 which forms the'boundary of the vertical cylindrical space which contains the hot air. Both the refractory masonry structure of the preheater wall and of the duct wall are only shown somewhat diagrammatically except where most exact detail is necessary for a good understanding of the invention. Those parts not shown in exact detail are embodied according to generally known and accepted principles.

The hot'air duct 4 pierces the refractory wall within the jacket Ito open into the space within the wall. The refractory wall within the jacket 1 consists of an innermost layer 14, a layer 15 surrounding the layer 14, both the layers 14,15. being of refractory brick,'and outside the layer 15 an insulating layer 8 which extends to the steel jacket 1. Layers 8, 14 and 15 are mutually separated by sliding joints 9,10.

The portions of the layers 14,15 immediately surrounding the duct 4 are constituted by rings 6,7 of bricks ll, 12 respectively, which are separated from each other and the ring 12 from the layer 8 portions of the sliding joints 9,100

It-will be clear from FIGS. land 2 that the layer 14, including the ring 6, and the layer 15, including the ring 7, are able to move in a vertical direction with respect to each other and withrespect to the further layer 8, and thus differences of expansion of the layers can be accommodated freely by displacements of the layers relative to each other in an essentially vertical direction.

, In the cold condition the structure will, looking axially along the duct 4, have two radial steps 16, 17 in the wall of the duct 4. However, after heating up to operatwall of duct 4 is a smooth and continuous surface of revolution. The sliding joints 9 and 10 are, during construction of the structure, sealed by refractory felt, which allows some movement of the layers with respect to each other and nevertheless provides an adequate seal to avoid the penetration of gases into the joints. A continuous insulating layer 8 is constructed in contact with the steel jacket 1 and with the steel wall 2 of the duct and will usually consist of porous bricks of fire clay brick (chamotte) type and quality. To obtain a distribution of temperatures over the steel jacket 1 and of the steelwall 2 which is as uniform as possible so that undesired heat stresses are avoided, it is preferable that the portion of the insulating layer 8 within the jacket 1 has an approximately equal thickness throughout, and the same is true for the portion of the layer 8 within the duct part 2. As the amount of insulation is not the same throughout, it is preferred to use material of different insulating coefficient instead of varying the thickness of the layer. This is, however, not essential for the successful application of the invention as such.

Lining the insulating layer 8 within the steel outlet duct wall 2 and providing the wall of the duct 4, is a layer 13 of masonry formed by refractory bricks of high quality. This layer 13 terminates at its end nearest the space within the stove at the sliding joint 10, and at its other end in the area of the flange 3, but the lyaer 13 does not extend as far as the outer face of the flange 3, so that the layer 13 can expand without compressing the sliding joints 9, 10 and putting the rings 6,7 of bricks 11,12 under axial pressure.

As can be seen in FIG. 3 adjacent bricks 11 of the ring 6, have, in their mutually abutting surfaces, projections 18,19 received in corresponding recesses so that a good interlocking is obtained in the ring 6.

As shown in FIG. 4 there are recesses and corresponding projections 18,19 not only in bricks 11 of the ring 6, but also in the bricks 12 of the ring 7.

The two projections 18,19 (and the corresponding recesses) of any one brick are not parallel, but run at an angle to each other, whereby a very sound interlocking of the bricks against relative movement is obtained.

From FIG. 1, it can be seen that those face of the bricks ll, 12 which are opposite the faces forming part of the bounding surface of the gas duct and which abut other bricks of the layer 14,15 are all in planes substantially perpendicular to the curved inner surface 5 of the wall. This arrangement effectively wedges the rings 6,7 so thatthey are restrained from movement into the hot gas space.

I claim:

1. A refractory masonry wall structure bounding a space which receives hot gas which comprises a refractory masonry wall, a gas duct connection passing through said wall forming an entrance thereinto, at least one layer of refractory masonry circumferentially surrounding said gas duct connection at its entry through said wall, said masonry including an inner ring of refractory bricks, and a layer of insulating masonry material outwardly adjacent to said refractory layer circumferentially surrounding said gas duct connection, and a sliding joint between said refractory masonry layer including said ring of brick and said insulating masonry layer to permit relative sliding movement of said layers in a vertical direction with respect to one another.

2. A wall structure in accordance with claim 1 wherein said refractory masonry layer includes a first inner ring of refractory bricks and an outwardly adjacent second inner ring of refractory brick, and a sliding joint between said first and said second inner rings of brick to permit relative sliding movement of said first and second inner rings in a vertical direction with respect to one another.

3. A wall structure in accordance with claim 1 wherein said ring of bricks in the cold condition of the wall is offset transversely with respect to the duct from the desired position in alignment with the duct by an amount such that, on heating to operating temperature, the expansion of the layer'of which the inner ring is a portion thereof brings the ring into the desired aligned position.

4. A wall structure in accordance with claims 1 wherein the bricks in the inner ring have interlocking projections and recesses in their mutually abutting surfaces.

5. A wall structure in accordance with claim 2 wherein the adjacent ring of inner bricks has two pairs of interlocking projections and recesses, one pair extending longitudinally at an angle to the other pair.

6. A wall structure in accordance with claim 1 wherein the region of said wall where the gas duct enters the hot gas space has its inner face curved and theinner ring of bricks have, opposite the faces thereof which face into the gas duct connection, faces which are in planes substantially perpendicular to the said inner face.

7. A wall structure in accordance with claim 1 wherein the gas duct connection, furthermost from the hot gas space from the said inner ring of bricks, is

bounded by masonry which is jointed to the adjacent inner ring of bricks by a joint allowing relative sliding and is provided with an expansion gap to allow expansion in the direction away from the hot gas space. Y

8. A wall structure in accordance with claim 1 wherein ceramic wool or refractory felt is positioned in said sliding joint.

9. Apparatus for preheating air for a blast furnace comprising a regenerator stove havine a refractory masonry wall structure bounding a space which receives hot gas which comprises a refractory masonry wall, a

gas duct connection passing through said wall forming an entrance thereinto, at least one layer of refractory masonry circumferentially surrounding said gas duct connection at its entry through said wall, said masonry including an inner ring of refractory bricks, and a layer of insulating masonry material outwardly adjacent to said refractory layer circumferentially surrounding said gas duct connection, and a sliding joint between said refractory masonry layer including said ring of brick and said insulating masonry layer to permit relative sliding movement of said layers in a vertical direction with respect to one another. 

1. A refractory masonry wall structure bounding a space which receives hot gas which comprises a refractory masonry wall, a gas duct connection passing through said wall forming an entrance thereinto, at least one layer of refractory masonry circumferentially surrounding said gas duct connection at its entry through said wall, said masonry including an inner ring of refractory bricks, and a layer of insulating masonry material outwardly adjacent to said refractory layer circumferentially surrounding said gas duct connection, and a sliding joint between said refractory masonry layer including said ring of brick and said insulating masonry layer to permit relative sliding movement of said layers in a vertical direction with respect to one another.
 2. A wall structure in accordance with claim 1 wherein said refractory masonry layer includes a first inner ring of refractory bricks and an outwardly adjacent second inner ring of refractory brick, and a sliding joint between said first and said second inner rings of brick to permit relative sliding movement of said first and second inner rings in a vertical direction with respect to one another.
 3. A wall structure in accordance with claim 1 wherein said ring of bricks in the cold condition of the wall is offset transversely with respect to the duct from the desired position in alignment with the duct by an amount such that, on heating to operating temperature, the expansion of the layer of which the inner ring is a portion thereof brings the ring into the desired aligned position.
 4. A wall structure in accordance with claims 1 wherein the bricks in the inner ring have interlocking projections and recesses in their mutually abutting surfaces.
 5. A wall structure in accordance with claim 2 wherein the adjacent ring of inner bricks has two pairs of interlocking projections and recesses, one pair extending longitudinally at an angle to the other pair.
 6. A wall structure in accordance with claim 1 wherein the region of said wall where the gas duct enters the hot gas space has its inner face curved and the inner ring of bricks have, opposite the faces thereof which face into the gas duct connection, faces which are in planes substantially perpendicular to the said inner face.
 7. A wall structure in accordance with claim 1 wherein the gas duct connection, furthermost from the hot gas space from the said inner ring of bricks, is bounded by masonry which is jointed to the adjacent inner ring of bricks by a joint allowing relative sliding and is provided with an expansion gap to allow expansion in the direction away from the hot gas space.
 8. A wall structure in accordance with claim 1 wherein ceramic wool or refractory felt is positioned in said sliding joint.
 9. Apparatus for preheating air for a blast furnace comprising a regenerator stove havine a refractory masonry wall structure bounding a space which receives hot gas which comprises a refractory masonry wall, a gas duct connection passing through said wall forming an entrance thereinto, at least one layer of refractory masonry circumferentially surrounding said gas duct connection at its entry through said wall, said masonry including an inner ring of refractory bricks, and a layer of insulating masonry material outwardly adjacent to said refractory layer circumferentially surrounding said gas duct connection, and a sliding joint between said refractory masonry layer including said ring of brick and said insulating masonry layer to permit relative sliding movement of said layers in a vertical direction with respect to one another. 